Can a complete heart block (CHB) contribute to the development of heart failure with preserved ejection fraction (HFpEF) in patients with underlying conditions such as hypertension, diabetes, or coronary artery disease?

Complete Heart Block and HFpEF: Not a Direct Cause, But a Diagnostic Mimic

Complete heart block (CHB) does not cause heart failure with preserved ejection fraction (HFpEF); rather, it represents a distinct diagnostic entity that must be excluded when evaluating patients with suspected HFpEF, as CHB can mimic HFpEF symptoms but requires fundamentally different treatment (pacemaker therapy). 1

CHB as a HFpEF Mimic Requiring Exclusion

The 2023 ACC Expert Consensus explicitly categorizes high-degree atrioventricular block as a HFpEF mimic that must be identified during diagnostic evaluation, particularly in patients younger than 60 years. 1 This classification is critical because:

• CHB can present with congestive symptoms (dyspnea, exercise intolerance, fatigue) that superficially resemble HFpEF but stem from bradycardia-induced low cardiac output rather than diastolic dysfunction. 1

• The treatment paradigm is entirely different: CHB requires permanent pacemaker implantation, whereas HFpEF requires SGLT2 inhibitors, diuretics, and comorbidity management. 1, 2

• Misdiagnosing CHB as HFpEF leads to inappropriate therapy and delays definitive treatment that can restore normal cardiac output and resolve symptoms. 1

Diagnostic Clues to Distinguish CHB from True HFpEF

When evaluating patients with suspected HFpEF, actively screen for CHB by looking for:

• Marked bradycardia (heart rate typically <40-50 bpm at rest) that is inappropriate for the clinical context. 1

• ECG findings showing complete dissociation between P waves and QRS complexes, with a slow ventricular escape rhythm. 1

• Age <60 years should heighten suspicion, as this is specifically flagged as a diagnostic clue for CHB mimicking HFpEF. 1

• Symptoms that improve dramatically with temporary pacing during diagnostic evaluation, confirming CHB as the primary problem rather than diastolic dysfunction. 1

The True Risk Factors for HFpEF Development

Actual HFpEF develops from a constellation of metabolic and cardiovascular comorbidities, not from conduction system disease:

• Hypertension is the major risk factor for HFpEF development and is highly prevalent in those with established HFpEF. 1

• Obesity is present in >80% of HFpEF patients, with excess intra-abdominal fat playing a pivotal role in the obese/metabolic HFpEF phenotype. 1

• Diabetes affects 25-50% of HFpEF patients and confers adverse prognosis through neurohormonal activation, inflammation, and impaired skeletal muscle function. 1

• Coronary artery disease is common in HFpEF and associates with greater deterioration in left ventricular systolic function and worse outcomes. 1

• Aging and reduced physical activity are important contributors to HFpEF development. 1

Clinical Implications for Practice

When encountering a patient with dyspnea, exercise intolerance, and preserved ejection fraction:

• Obtain a 12-lead ECG immediately to exclude CHB and other conduction abnormalities before labeling the patient as having HFpEF. 1, 2

• If CHB is present, refer urgently for permanent pacemaker implantation rather than initiating HFpEF-directed medical therapy. 1

• If CHB is absent and true HFpEF is confirmed, initiate SGLT2 inhibitors (empagliflozin or dapagliflozin) as first-line disease-modifying therapy, which reduce heart failure hospitalizations by approximately 20%. 2, 3, 4

• Address underlying comorbidities including hypertension (target BP <130/80 mmHg), diabetes (preferentially with SGLT2 inhibitors), and obesity (through exercise training and weight loss). 2, 4

Common Pitfall to Avoid

The critical error is attributing congestive symptoms to HFpEF without first excluding CHB and other mimics. 1 This leads to:

• Delayed pacemaker therapy in patients who could have immediate symptom resolution. 1

• Inappropriate escalation of diuretics and other HFpEF medications that do not address the underlying bradycardia. 1

• Missed opportunity for definitive treatment of a reversible cause of heart failure symptoms. 1

The diagnostic table from the ACC explicitly lists CHB alongside cardiac amyloidosis, hypertrophic cardiomyopathy, and other conditions that must be systematically excluded before confirming HFpEF diagnosis. 1